A missile warhead that exploded outside the cockpit brought down Malaysia Airlines Flight 17 over Ukraine, a Dutch report released Tuesday found.

All 298 people aboard the aircraft died in the July 2014 crash.

Dutch Safety Board chairman Tjibbe Joustra said the warhead fit a Buk rocket system, referring to Russian military technology. But Russian officials who participated in the investigation said it was not possible to confirm the warhead or type of system, according to Joustra.

Joustra said that “none of the aviation parties involved” — including Ukrainian authorities who failed to close off the airspace — “recognized the risks posed to civil aviation by the armed conflict on the ground.” He said the parties viewed the conflict from a military perspective and nobody considered the risk to civil aviation.

“As a precaution, there was sufficient reason for Ukraine authorities to close the airspace above the eastern part of the country” where armed conflict was taking place , Joustra said at Gilze-Rijen airbase in the Netherlands.

Speaking later Tuesday, Dutch Prime Minister Mark Rutte said of those who took down the plane: “We must do the utmost so that the people who did it will not avoid … punishment.”

Rutte added that the investigation has had “an enormous impact” on the Netherlands’ relationship with Russia.

“What I would really like to do is to call on the Russian authorities to respect and also give full cooperation to this report and the continued investigation that the criminal prosecutors are doing,” he told reporters Tuesday.

Boeing 777 was heading from Amsterdam to Malaysia

Experts investigating the crash of Malaysia Airlines Flight 17 in Ukraine are set to release their findings.

The Boeing 777 was heading from Amsterdam to Malaysia when it was shot down on July 17, 2014, over Ukrainian territory controlled by pro-Russian separatists.

The Dutch Safety Board has lead an international investigation into the crash, at the request of Ukraine, which remains locked in conflict with pro-Russian separatists in its eastern Donetsk and Luhansk regions.

Relatives of the crash victims were being informed of the findings ahead of the report’s release, the Dutch Safety Board said in a statement.

It said the report focused on four themes: “The causes of the crash, the issue of flying over conflict areas, the reasons why Dutch surviving relatives had to wait for two to four days for confirmation from the Dutch authorities that their loved ones had been on the aeroplane, and lastly the question to what extent the occupants of flight MH17 consciously experienced the crash. ”

The board said its investigation was not concerned with blame or liability, which fell to a separate criminal investigation.

In its preliminary report on the disaster, it said Flight 17 broke apart in the air after a burst of “high-energy objects” hit it from outside, supporting the theory that a warhead exploded close to the jet.

A draft report by the board said that evidence indicated that pro-Russian rebels shot down MH17 with a Russian-made Buk missile, a source who saw the document told CNN in July.

The disaster and its aftermath — when armed men initially prevented international monitors from reaching the crash site and recovering the scattered bodies — shocked the world.

The greatest loss was suffered by the Netherlands, which had 196 of its citizens on board the flight. Dozens of Malaysians and Australians were also on the plane, as were smaller numbers of UK, Indonesian, Belgian, German, Philippine and Canadian nationals.

Disputes over responsibility

Disputes over who is responsible have helped to sour relations between Moscow and the West.

Several Western nations and the Ukrainian government have accused pro-Russian separatists operating in the region of shooting down the plane with a missile.

Rebel leaders and the Russian government have repeatedly disputed those allegations, and have suggested instead that Ukrainian forces shot the plane down with either a surface-to-air missile or one of their own fighter jets.

Even before the MH17 disaster, Western nations accused Russia of supplying the rebels in Ukraine. The United States and the European Union imposed sanctions against Russia last year to punish it for this and its annexation of the Ukrainian peninsula of Crimea.

In July, Russia blocked a U.N. Security Council resolution that would have created an international tribunal to prosecute those responsible for bringing down MH17.

Separate criminal investigation

In addition to the Dutch Safety Board’s investigation, Dutch prosecutors are leading in international group of prosecutors — known as the Joint Investigation Team (JIT) — in a criminal investigation into the crash.

In August, the JIT said authorities were examining what could be surface-to-air missile parts that were found in the area where the plane went down.

The parts possibly come from a Russian-made Buk surface-to-air-missile system, it said in a statement. But the prosecutors warned that no conclusion could yet be drawn that the discovered parts have a causal connection to the MH17 crash.

Their criminal probe is expected to produce a report by the end of the year.